Systems and methods for underwater illumination, survey, and wireless optical communications

ABSTRACT

Embodiments of the present disclosure describe an underwater optical communication and illumination system employing laser diodes directly encoded with data, including spectrally efficient orthogonal frequency division multiplex quadrature amplitude modulation (QAM-OFDM) data. A broadband light source may be utilized to provide both illumination to an underwater field of interest and underwater optical communication from the field of interest to a remote location.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/679,898, now issued as U.S. Pat. No. 10,673,539 on Jun. 2, 2020.

BACKGROUND

Underwater human activities such as oceanography studies, offshore oilexploration, sea floor surveying and environmental monitoring haveincreased significantly. As a result, there is a growing need forreliable illumination and high data-rate underwater wirelesscommunication (UWOC) systems. Traditionally, visible light sources havebeen separate from underwater communication systems. A variety ofillumination devices are known, including for example, incandescent andLED sources. Acoustic communication systems are also well known.However, the bandwidth of an underwater acoustic channel is limited tohundreds of kHz because of strong frequency dependent attenuation ofsound in seawater. The slow propagation of sound waves causes large timedelay in acoustic communication systems. In addition, radio frequency(RF) communication is severely limited due to the conductivity ofseawater at radio frequencies.

SUMMARY

Optical-based UWOC systems have gained interest from military andacademic research communities and have been proposed as an alternativeor complementary solution to acoustic and RF underwater communicationlinks over short and moderate distances (less than 100 m). Technologicaladvances in visible light emitters, receivers, digital communicationsand signal processing now exploit the low absorption of seawater in theblue-green (400-550 nm) region of the visible light window ofelectromagnetic spectrum. A goal of an optical-based UWOC system is toprovide high data-rates to transmit large data capacity for versatileapplications such as underwater oil pipe inspection, remotely operatedvehicle (ROV) and sensor networks.

The underwater propagation of light is governed by attenuation which isa combined effect of absorption and scattering mechanisms. Because ofthe aquatic environment is optically very challenging, the effect ofmultiple scattering especially in turbid littoral waters stronglydegrades bit error rate (BER) performance of the on-off keying (OOK)based high data-rate UWOC systems.

In general, embodiments of the present disclosure describe an underwatervision (illumination) and wireless optical communication systememploying GaN based light source for giga-bit-per-second data rate overlong distance (5-20 meters and beyond). In some embodiments, a broadbandlight is composed of multiple wavelengths laser, for white-lightillumination and communications. In other embodiments of the presentdisclosure, a UWOC system utilizing a violet or blue laser combined withphosphor material in the transmitter module to generate white light, canbe used for both underwater vision and communications. The phosphormaterial used for white light generation refers to a kind of colorconversion material that can be excited by violet or blue laser andgenerate blue, green, yellow or red color. By mixing those colors, whitelight with different color rendering index and color temperature can beachieved. In yet other embodiments of the present disclosure, a UWOCsystem with red-green-blue (RGB) lasers can be utilized to generatelight at specific wavelength ranges. By mixing light from RGB lasers,light with different color rendering indices or color temperatures canbe achieved. In yet other embodiments of the present disclosure,ultraviolet (UV) lasers can be utilized to provide both illumination andnon-line-of-sight underwater communications.

Embodiments of the present disclosure further describe variousspectral-efficient techniques, such as orthogonal-frequency divisionmultiplexing, and spectral multiplexing techniques, including wavelengthdivision multiplexing, as well as low light detection methods for longdistance underwater communications.

Embodiments of the present invention include a light source used inconjunction with discrete optics to provide point-to-point underwaterdata communication and also to illuminate an underwater environment byproviding visible light useful, for example, to conduct underwaterexploration or other activities.

The details of one or more examples are set forth in the descriptionbelow. Other features, objects, and advantages will be apparent from thedescription and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

This written disclosure describes illustrative embodiments that arenon-limiting and non-exhaustive. In the drawings, which are notnecessarily drawn to scale, like numerals describe substantially similarcomponents throughout the several views. Like numerals having differentletter suffixes represent different instances of substantially similarcomponents. The drawings illustrate generally, by way of example, butnot by way of limitation, various embodiments discussed in the presentdocument.

Reference is made to illustrative embodiments that are depicted in thefigures, in which:

FIG. 1 illustrates a schematic of a laser diode (LD) based UWOC systemin accordance with one or more embodiment of the present invention.

FIG. 2 illustrates a conceptual block diagram of a 16-QAM-OFDM datageneration and underwater transmission system suitable for use with theembodiments of FIG. 1.

FIG. 3 is a table summarizing the related parameters of the 16-QAM-OFDMdata streams delivered by a TO-9 packaged blue LD, including symbollength, subcarrier frequency and subcarrier frequency interval underdifferent transmitted data rates.

FIG. 4 illustrates the operation of the 16-QAM-OFDM data which wasdirectly encoded onto the TO-9 packaged blue LD after offsetting by a DCbias current.

FIG. 5A illustrates a graphical view of light-current-voltage (LIV)characteristics of the TO-9 packaged LD.

FIG. 5B illustrates a graphical view of lasing spectra versus wavelengthat 250 C under different bias currents.

FIG. 6 illustrates the small-signal modulation response at differentbias currents of the blue laser diode.

FIG. 7A illustrates a graphical view of measured BER versus laser biascurrent.

FIG. 7B illustrates a graphical view of a constellation diagram at 70mA.

FIG. 8A illustrates a graphical view of measured BER of the 16-QAM-OFDMdata versus modulation bandwidth.

FIG. 8B illustrates a graphical view of measured electrical signal tonoise ratios (SNRs) of the received 16-QAM-OFDM data as a function ofsubcarrier index.

FIG. 8C illustrates a graphical view of a constellation map of 1.2-GHz16-QAM-OFDM signals transmitted over the 5.4-m underwater channel.

FIG. 9 illustrates a graphical view of measured BER versus link distancefor the 1.2-GHz 16-QAM-OFDM signals.

FIG. 10 illustrates a compact integrated underwater illumination, surveyand optical communication system in accordance with one or moreembodiments of the present disclosure.

DETAILED DESCRIPTION

The invention of the present disclosure relates to a laser diode-basedunderwater illumination and wireless optical communication (LD-UWOC)system. In one embodiment, a LD-UWOC system yields a data rate of 1.5Gbps over a 20-meters underwater channel based on a simplenon-return-to-zero on-off-keying (NRZ-OOK) modulation scheme. In anotherembodiment, a 16-quadrature amplitude modulation-orthogonal frequencydivision multiplexed (QAM-OFDM) based LD-UWOC system, yields a data rateof 4.8 Gbit/s over a 5.4-m transmission distance. For a NRZ-OOK basedLD-WUOC system, a high-speed UWOC link offered a data rate up to 2 Gbpsover a 12-meter-long, and 1.5 Gbps over a recorded 20-meter-longunderwater channel. The measured bit-error rate (BER) are 2.8×10-5, and3.0×10-3, respectively, satisfying forward error correction (FEC)criterion. For a 16-QAM-OFDM based LD-UWOC system, an error vectormagnitude (EVM) and signal-to-noise ratio (SNR) of 16.5% and 15.63 dB,respectively, were measured with a corresponding BER is 2.6×10-3. Inaddition, experimental results reveal that the scattering has minimaleffect on BER performance of the transmitted 1.2-GHz 16-QAM-OFDM signalsfor a link distance of up to 5.4-m in clear water. Therefore, longerunderwater transmission is possible by simply increasing the power ofthe laser diode.

In some embodiments of the present disclosure, blue-light laser diodeswere used as the illumination source and a Si avalanche photodetectorwas used in conjunction with discrete optics without the need of adiffuser. The data was encoded using a cost-effective modulationtechnique, for example, the non-return-to-zero on-off-keying (NRZ-OOK)modulation, and a spectral-efficient modulation technique, for example,the orthogonal frequency division multiplexed quadrature amplitudemodulation (QAM-OFDM) for high-speed point-to-point data communicationunderwater.

Orthogonal frequency-division multiplexing (OFDM) is a method ofencoding digital data on multiple carrier frequencies. OFDM is afrequency-division multiplexing scheme used as a digital multi-carriermodulation method. A large number of closely spaced orthogonalsub-carrier signals are used to carry data on several parallel datastreams or channels. Each sub-carrier is modulated with a conventionalmodulation scheme (such as quadrature amplitude modulation orphase-shift keying) at a low symbol rate, maintaining total data ratessimilar to conventional single-carrier modulation schemes in the samebandwidth.

Embodiments of the present disclosure further describe an underwaterillumination and wireless optical communication system based on directmodulation of GaN-based LDs utilizing the on-off-keying (OOK) or otherspectral-efficient modulation techniques, such as the orthogonalfrequency division multiplexing (OFDM) technique. Embodiments furtherdescribe a focused (point-to-point) high-speed communication link.

In some embodiments of the present disclosure, GaN-based violet-bluelaser diodes (LDs) were used as a high power light source and high speedunderwater data communication. By combining phosphor materials in theUWOC system, white light can be generated to serve as light source forvision application at the same time.

FIG. 1 is a schematic of one or more embodiments of the presentdisclosure with a laser diode (LD) based UWOC system employing a 450 nmlaser diode 10 in the transmitter module 12 and a Si avalanchephotodetector 14 in the receiver module 16. The data stream is amplifiedby amplifier 18 before combining at bias-tee 20 with DC bias provided bythe DC power supply 22 to drive laser diode 10 (Thorlabs LP450-SF15,output power of 15 mW biasing at 137 mA). A pair of plano-convex lenses24, 26 are used in both transmission module 12 and receiver module 16.Lenses 24, 26 (Thorlabs LA1951-a) have 25.4 mm diameter and 25.4 mmfocal length to produce a parallel free-space beam. The laser beampasses through the water channel 30 and is received by photodetector 14(Menlo Systems APD210) having an active diameter of 0.5 mm, aresponsivity of 5 A/W at 450 nm and a noise equivalent power (NEP) of0.4 pW/Hz^(1/2).

One embodiment of the present disclosure describes a high-speed UWOClink offering a data rate up to 2 Gbps over a 12-meter-long, and 1.5Gbps over a recorded 20-meter-long underwater channel has been achieved.To demonstrate the UWOC system based on OOK modulation scheme, a patterngenerator was used to generate the pseudorandom binary sequence (PRBS)2¹⁰−1 data stream in the transmitter module 12, and the data stream isamplified by the 28 dB driver amplifier before connecting with the 15GHz broadband bias-tee. The bit-error rate (BER) for the UWOC system at2 Gbps over a 9-m, at 2 Gbps over a 12-m, and at 1.5 Gbps over a 20-munderwater channel was measured to be 1.2×10⁻⁶, 2.8×10⁻⁵, and 3.0×10⁻³,respectively, all passing the forward error correction (FEC) limit. Openeye diagrams and measured FEC compliant BER for a data rate of up to 2Gbps were successfully achieved for a 9-meter as well as a 12-meter UWOClink.

Another embodiment of the present disclosure describes underwaterwireless optical transmission at 4.8 Gbit/s over 5.4-m link usinghigh-spectral efficient 16-QAM-OFDM modulation scheme. For testing theunderwater wireless optical transmission system using the high-spectralefficient 16-QAM-OFDM modulation scheme, an arbitrary waveform generator(AWG) was used for signal generation and a digital serial analyzer (DSA)was used for analyzing the received signal. The 16-QAM-OFDM signals withcorresponding subcarriers were generated by an offline MATLAB programand sampled by an arbitrary waveform generator with a sampling rate of24 GS a/s.

A conceptual block diagram of the 16-QAM-OFDM data generation andunderwater transmission system is illustrated in FIG. 2. Binary bitsequence 40 is divided into parallel low-speed data blocks via serial toparallel module 42 and mapped into QAM symbols via symbol mapping module44. Inverse fast Fourier transform (IFFT) module 46 converts the QAMsymbols into temporal OFDM signals with a FFT size of 512 and provides aparallel signal to parallel to serial module 48. A cyclic prefix (CP) of1/32 is added via cyclic prefix module 50 to mitigate inter-symbolinterference (ISI) in the transmission link. FIG. 3 is a tablesummarizing the related parameters of the 16-QAM-OFDM data streamsdelivered by the TO-9 packaged blue LD, including symbol length,subcarrier frequency and subcarrier frequency interval under differenttransmitted data rates.

After digital-to-analog conversion (DAC) at module 52, the QAM-OFDMsignals are electrically pre-amplified and directly encode the TO-9packaged blue LD. In one embodiment, the QAM-OFDM signals werepre-amplified with a 26-dB broadband amplifier (Picosecond Pulse Labs,5865) and then superimposed on the DC bias current using the RFconnector of the built-in Bias-tee within the diode mount (ThorlabsLDM91P), which directly encodes the TO-9 packaged blue LD. The DC biaspoint of the TO-9 packaged blue LD was optimized for achieving largestpeak-to-average power ratio (PAPR) of the modulated QAM-OFDM datastream. Electrical-to-optical domain conversion was performed accordingto the power-to-current response of the blue LD, leading to the optical16-QAM-OFDM data stream with its maximal/minimal power levels determinedby the maximal/minimal current levels. FIG. 4 illustrates the operationof the 16-QAM-OFDM data which was directly encoded onto the TO-9packaged blue LD after offsetting by a DC bias current.

The collimated laser beam with an estimated divergence angle of 5.6° wasthen transmitted through water channel 60 filled with fresh tap water,similar to a clear ocean water type. A 15 mW (11.8 dBm) output power LD54 would be sufficient to overcome the attenuation in clear oceanwaters. The water tank with 0.6-m×0.3-m×0.3-m dimensions was made ofglass. The physical light propagation distance was extended up to 5.4-mby using reflective mirrors installed at both ends of the tank. Withusing a 50-mm focal length lens, the output signal from the waterchannel was focused into a high sensitivity APD 62 with an activediameter of 0.5-mm, and a responsivity of −5 A/W at 450 nm. The powerlevel of transmitted laser light was controlled via neutral densityfilters.

After optical-electrical conversion, the received analog waveform wascaptured by digital serial analyzer 64 with a sampling rate of 100 GSa/sand converted to digital signals. After the removal of the cyclic prefixat module 66 and further processing by serial to parallel module 68, thereceived OFDM signals are passed to FFT module 70, which converts tofrequency-domain subcarriers and re-maps back to QAM symbols via symboldemapping module 72. Finally, parallel-to-serial module 74 was employedto convert the QAM symbols into serial on-off keying data 76.Constellation diagram, error vector magnitude (EVM), signal-to-noiseratio (SNR) and bit error rate (BER) were measured and used to evaluatethe performance of this underwater wireless optical communicationsystem. All measurements were taken under normal room illumination andno optical interference filter was used to suppress the ambient light.

The light-current-voltage (LIV) characteristics of the TO-9 packaged andfiber-pigtailed blue LD is illustrated in FIG. 5A. The threshold currentand differential quantum efficiency was 3 mmA and 0.27 W/A,respectively. FIG. 5B illustrates lasing spectra versus wavelength at250 C under different bias currents. Bias currents were measured usingan Ocean Optics HR4000 Spectrometer. The nominal spectral width of theblue LD was 0.9 nm. The peak emitting wavelength was observed around448.4 nm with the blue LD biased at 40 mA and was slightly red-shiftedwith increasing the bias current. The optimum wavelength of operation inan underwater optical link would depend on the water turbidity whichvaries widely between geographic locations.

The overall frequency response of the system including laser driver 54,underwater channel 60, and APD 62 was evaluated to determine the maximumallowable modulation bandwidth for encoding the OFDM signals. FIG. 6represents the small-signal modulation response at different biascurrents of the blue LD 54, which was measured by using a vector networkanalyzer. When the bias current was increased, no significant extensionin LD modulation bandwidth is observed due to the combined bandwidthlimitations of the LD driver 54 and the 1-GHz cut-off frequency of theAPD 62. The decreased throughput intensity at high frequency region wasalso due to bandwidth constraints. As a result, these limitations set anupper limitation on the allowable OFDM bandwidth. The maximum −3 dBbandwidth occurred around 1.1 GHz, as indicated by the dash line in thefigure.

The performance of the blue LD 54 with 1-GHz 16-QAM-OFDM data atdifferent bias currents was initially evaluated in free-space. Both thelaser bias current and the amplitude of modulating signal was adjustedto evaluate the optimized operating condition. At low bias operation,the clipping of modulating signal degrades the BER of encoded16-QAM-OFDM data. In addition, overly driving the blue LD decreased thethroughput response and ultimately degraded the high-frequencysubcarrier power of the 16-QAM-OFDM data, resulting in an increasedtransmitted BER. The highest data rate was achieved when the biascurrent of blue LD and the peak-to-peak voltage of modulating signal wasset to Vbias=5.01 V (Ibias=70 mA) and Vpp=0.4 V, respectively.

FIG. 7A and FIG. 7B illustrate BER performance of the blue LD 54delivered 1-GHz 16-QAM-OFDM data as a function of laser bias current andthe constellation diagram at 70 mA. FIG. 7A illustrates measured BERversus laser bias current. FIG. 7B illustrates a constellation diagramat 70 mA.

To implement the underwater 16-QAM-OFDM transmission, the bias currentof the blue LD 54 was maintained at the optimized operating condition of70 mA. To evaluate the overall 16-QAM-OFDM transmission performance overthe 5.4-m underwater communication channel, the measured BER, SNR andconstellation plot are shown in FIG. 8A, FIG. 8B and FIG. 8C.

FIG. 8A illustrates the measured BER of the 16-QAM-OFDM data versusmodulation bandwidth. As illustrated, increasing the data bandwidth from0.8 to 1.2 GHz enlarged the transmission capacity of the TO-9 packagedand fiber-pigtailed blue LD from 3.2 Gbit/s to 4.8 Gbit/s at the expenseof degraded BER from 6.8×10⁻⁴ to 2.6×10⁻³. Further increasing the databandwidth to 1.3 GHz lead to an increased BER of 4.8×10⁻³, which wasslightly above the FEC required BER of 3.8×10⁻³. Therefore, to meet theFEC criterion, the acceptable bandwidth for the carried 16-QAM-OFDM was1.2 GHz and the corresponding data rate was 4.8 Gbit/s.

FIG. 8B illustrates the measured electrical signal to noise ratios(SNRs) of the received 16-QAM-OFDM data as a function of subcarrierindex. The measured SNR profile exhibited a negative slope and followedthe overall frequency response depicted in FIG. 3. The SNR maintainedhigh values at small subcarrier indices (low frequencies) and wasinversely proportional to the subcarrier index. The average SNR at 70 mAwas around 15.6 dB, which was higher than that of 15.19 dB required bythe FEC decoding.

FIG. 8C illustrates the constellation map of 1.2-GHz 16-QAM-OFDM signalstransmitted over the 5.4-m underwater channel. As shown in the figure, aclear constellation diagram can be obtained.

Scattering effects, such as the temporal pulse spread (inter-symbolinterference), were also evaluated in relation to overall systemperformance FIG. 9 illustrates the measured BER versus link distance forthe 1.2-GHz 16-QAM-OFDM signals. The aim of this evaluation was toevaluate if the BER performance deteriorated as a function of linkdistance. It should be noted that the receiving optical power was keptconstant by using a variable attenuator as the link distance wasincreased from 0.6 to 5.4 m. As shown in FIG. 9, a relatively flat BERwas observed.

This example of a UWOC system required good pointing accuracy betweenthe transmitter and receiver because the transmitter beam is collimatedwith a very small diameter. Expanding the transmitter beam to reduce thepointing accuracy requirement would result in a weaker beam at thereceiver that would reduce the performance at longer ranges. In moreturbid waters, scattering increases because of high concentration oforganic and inorganic particulates and can cause significant temporaldispersion which can be thought of as a form of inter-symbolinterference that will reduce the pointing accuracy because the beamwill spread out leading to low SNR and poor BER. However, experimentalresults show that the scattering has no effect on BER performance of1.2-GHz 16-QAM-OFDM signals during 5.4-m clear water communication link.For a 4.8 Gbit/s UWOC system, both the measured EVM of 16.5% and BER of2.6×10⁻³ pass the FEC criterion.

FIG. 10 depicts a compact integrated underwater illumination, survey andoptical communication system of the present invention. A power supply170, control circuit 172, laser diode module 174, and focusing optics176 can be embedded in the water-proof housing 178. The laser diodemodule 174 can have an integrated receiver unit for vision, and distanceranging measurement. The control circuit 172 integrates thefunctionalities of power stabilization, signal amplification andbias-tee combination to drive the laser diode unit 174. Phosphormaterial can be combined within the focusing optics to enable whitelight generation.

In other embodiments of the present disclosure, the transmitter modulecould be of different degree of coherency, such as edge-emitting laser,vertical-cavity surface emitting laser, and superluminescent diode. Thetransmitter module could be in standalone form or array form to increasethe optical output power. In embodiments of the present disclosure, asingle-mode 450 nm laser diode yielded favorable performance as comparedto a multimode 405 nm violet laser.

The transmitting medium includes, but is not limited to, water, oil, andother organic liquid. The laser wavelength can cover a wide range ofwavelength tailored to the specific low absorption and scattering natureof the transmitting medium.

In other embodiments, the photodetector can be an amplified biasedphotodetector, or a biased photodetector, or a UV-enhanced biasedphotodetector. The photodetector can be a photodetector based on, butnot limited to, Si, or GaAs, or GaN or other III/V materials.

In some embodiments of the present disclosure, the receiver module caninclude one or multiple photodetectors. A UWOC system, when utilizingmultiple laser diodes in the transmitter module and/or multiplephotodetectors in the receiver module, may achieve a higher data rate (5Gbit/s or above) and longer transmission distance (20 meters and above)when using an optical multi-input multi-output (MIMO) technique. A UWOCsystem, when utilizing multiple laser diodes in the transmitter moduleand/or multiple photodetectors in the receiver module, may achieve ahigher data rate (5 Gbit/s or above) using wavelength divisionmultiplexing (WDM) technique.

In other embodiments of the present disclosure, a UWOC system utilizingmultiple laser diodes, including at least two of violet, blue, green,yellow, and red emitting laser diodes, may generate white light for bothvision and communications underwater.

In still other embodiments of the present disclosure, a UWOC systemutilizing a violet or blue laser combined with phosphor material in thetransmitter module to generate white light, can be used for bothunderwater vision and communications. The phosphor material used forwhite light generation refers to a kind of color conversion materialthat can be excited by violet or blue laser and generate blue, green,yellow or red color. By mixing those colors, white light with differentcolor rendering index and color temperature can be achieved. In otherembodiments of the present disclosure, a UWOC system utilizingred-green-blue (RGB) lasers can be utilized to generate light atspecific wavelength ranges. By mixing light from RGB lasers, light withdifferent color rendering indices or color temperatures can be achieved.In yet other embodiments of the present disclosure, ultraviolet (UV)lasers can be utilized to provide both illumination andnon-line-of-sight underwater communications.

What is claimed is:
 1. A method of providing an underwater illuminationsource and data communication system, the method comprising: generatinga signal to drive multiple laser diodes in a transmitter module toprovide a white light illumination field of sufficient intensity andduration to illuminate an underwater field of interest during anunderwater activity, with said laser diodes being contained in awaterproof housing along with a control circuit and focusing optics, andsaid multiple laser diodes serving as a white light source to illuminatean underwater structure for an underwater vision application; andutilizing the multiple laser diodes, control circuit and focusing opticsin an optical communications systems to also convey information awayfrom the underwater field of interest while simultaneously continuing toilluminate the underwater field of interest with white light, saidutilizing including: with said focusing optics, optically directing atleast some of the light from said multiple laser diodes away from thewaterproof housing and toward a remote underwater location; at saidremote underwater location, receiving said at least some of theoptically-directed light and further processing received light into aninformation signal to yield an optically-delivered data stream duringsaid underwater activity; and at a receiver module contained within thewater-proof housing, receiving light from the remote underwater locationto conduct duplex communication using a plurality of photodetectorswithin the receiver module.
 2. The method of claim 1, wherein the fieldof interest includes an underwater vehicle, a diver, or a sea floor. 3.The method of claim 2, wherein said optically directing includesfocusing a light beam and directing a focused light beam toward theremote underwater location.
 4. The method of claim 3, wherein thefocused light beam defines a plurality of parallel beams.
 5. The methodof claim 4, wherein said receiving including directing the light beamonto a silicon-based avalanche photodiode.
 6. The method of claim 1,wherein said optical communication systems includes a spectrallyefficient modulation scheme.
 7. The method of claim 6 wherein themodulation scheme includes QAM-OFDM.
 8. The method of claim 1, whereinsaid multiple laser diodes includes a plurality of violet or blue lightlasers and a phosphor material is used to color convert light from theplurality of violet or blue light lasers into white light.
 9. The methodof claim 1, wherein said waterproof housing also includes a power supplyfor said multiple laser diodes.
 10. The method of claim 1, wherein saidmultiple laser diodes includes an ultraviolet laser.
 11. An underwaterlight system comprising: a waterproof housing; a transmitter modulecontained in the housing and receiving a data stream and controlling alaser diode light source to provide an optical signal and to provideillumination to serve as a white light source for an underwater visionapplication at the same time, with said underwater vision applicationremotely viewing an underwater structure; a transmitter lens within thehousing for focusing and directing the optical signal toward a remoteunderwater location; a first receiver module at the remote location forreceiving and processing the optical signal to yield the data streamwhile said light source simultaneously illuminates the underwaterstructure to conduct remote underwater vision proximate to the lightsource; and a second receiver module within the waterproof housingcontaining a plurality of photodetectors receiving light from the remoteunderwater location to conduct communication with the remote underwaterlocation.
 12. The light system of claim 11, wherein the first receivingmodule includes a receiver lens for focusing the optical signal toward asilicon avalanche photodiode.
 13. The light system of claim 11, whereinthe light source is housed on an underwater vehicle or structure ordiver.
 14. The light system of claim 11, wherein the waterproof housingalso contains a power supply and a control circuit for the laser diodelight source.
 15. The light system of claim 11, wherein the transmittermodule processes the data stream with a spectrally efficient modulationscheme to increase a data delivery rate.
 16. The light system of claim11, wherein the light source includes red, green and blue lasers.
 17. Anunderwater light system comprising: a transmitter contained in awaterproof housing and receiving a data stream and controlling a laserdiode light source to provide an optical signal; a lens within thewaterproof housing for focusing and directing the optical signal towarda remote underwater location; a first receiver at the remote locationfor receiving and processing the optical signal to yield the data streamwhile said laser diode light source simultaneously illuminates a fieldof interest with white light of sufficient intensity and duration toconduct remote underwater observation proximate to the light sourceusing a remote underwater vision device; and a second receiver withinthe waterproof housing containing a plurality of photodetectorsreceiving light from the remote underwater location to conductcommunication with the remote underwater location.
 18. The underwaterlight system of claim 17 further comprising a receiver lens for focusingand directing the optical signal toward a photodiode.
 19. The underwaterlight system of claim 17 wherein the light source includes red, greenand blue lasers or an ultraviolet laser.
 20. The underwater light systemof claim 17 wherein the waterproof housing contains a power supply forthe laser diode light source.